Project summary Increasing access to preventive and therapeutic oral health services is among the objectives of Healthy People 2020. Disparities in access to these services exist for disadvantaged populations, particularly in rural communities. The proposed research frames oral health care disparities as a complex system with multiple interacting individual and contextual factors. This research is timely in providing important information for future dental workforce preparation to address needs in rural areas. This study will also inform states in designing dental benefits for adults in implementing health reform initiatives. The proposed study will use data from the Medical Expenditure Panel Survey (MEPS) (1999- 2015) and the Area Health Resource Files (AHRF). The three specific aims of the study are: Aim 1: Identify trends in urban-rural (/racial/ethnic) differences in dental services and provider types. Aim 2: Define the contributions and cross-level interactions of individual and contextual factors (e.g. per capita dentists) related to dental services and providers. Aim 3: Assess the effects of Medicaid expansion on oral health care disparities among adults. Our study will establish a trend of urban-rural disparities in the type of dental services individuals receive and differences in the types of dental providers, and provide baseline data on the effects of Medicaid expansion (Aims 1 & 3). This study will contribute to a better understanding of facilitators and barriers to oral health care (Aim 2). Collectively, the study will provide evidence on rural-urban/racial/ethnic disparities in dental services in the US, which can inform current and future initiatives to improve oral health in rural communities. The results are expected to have a positive impact by providing high-quality information on oral health care in the US for better planning of oral health care and dental workforce development and distribution.